Gradient microstructure characteristics and mechanical properties of hardened cast iron obtained by various explosive impact pressures

Explosive processing yields high performance for crystal structure and mechanical properties of metals, and this work investigated the corresponding improvement for cast iron yielded by various explosive shock loading. Noticeably gradient enhanced surface could be consistently obtained by civilian explosive in both past and present works. Under the emulsion explosive produced shock wave, the iron surface were hardened with the most distinguished gradient features including strength, hardness, in which the engineering tensile strength of the outmost 0.5 mm layer reached 760 MPa, and the grain size of the outmost 160 μm layer presented gradient distribution and was refined to around 200 nm in minimum accompanied by twin dislocations and phase transition. Dislocation evolution molecular dynamics simulation clarified that the Shockley partial dislocations proportion accumulated with shock loading time, indicating the producing potential of the twin dislocations under properly enhanced impact, and revealing the different strengthening process dominated by phase transformation and non-phase transformation under different impact conditions. • Gradient hardened iron surface reliably obtained by civilian explosive blasting. • Mechanical improvements exhibited by multi featured characterizations. • Effect of impact pressure on gradient phenomenon were experimented. • Strengthening process affected by incremental impact pressure was simulated.